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Open Access Highly Accessed Research article

Derivation and validation of a simple, accurate and robust prediction rule for risk of mortality in patients with Clostridium difficile infection

Emma Butt1, Jane AH Foster2, Edward Keedwell3*, Julia EA Bell4, Richard W Titball1, Aneel Bhangu5, Stephen L Michell1 and Ray Sheridan6

Author Affiliations

1 Biosciences, College of Life and Environmental Sciences, Geoffrey Pope Building, University of Exeter, Stocker Road, Exeter EX4 4QD, UK

2 Diabetes and Vascular Medicine Research, Institute of Biomedical and Clinical Science, Peninsula Medical School, Barrack Road, Exeter EX2 5AX, UK

3 College of Engineering, Mathematics and Physical Sciences, Harrison Building, University of Exeter, North Park Road, Exeter EX4 4QF, UK

4 Geriatrics and General (Internal) Medicine, South West Peninsula Geriatrics Training Programme, William Wright House, Royal Devon and Exeter NHS Foundation Trust, RD&E Hospital, Barrack Road, Exeter, Devon EX2 5DW, UK

5 General Surgery Registrar Rotation, West Midlands Deanery, Edgbaston, Birmingham B16 9RG, UK

6 William Wright House, Royal Devon and Exeter NHS Foundation Trust, RD&E Hospital, Barrack Road, Exeter, Devon EX2 5DW, UK

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BMC Infectious Diseases 2013, 13:316  doi:10.1186/1471-2334-13-316

Published: 12 July 2013

Abstract

Background

Clostridium difficile infection poses a significant healthcare burden. However, the derivation of a simple, evidence based prediction rule to assist patient management has not yet been described.

This study aimed to identify such a prediction rule to stratify hospital inpatients according to risk of all-cause mortality, at initial diagnosis of infection.

Method

Univariate, multivariate and decision tree procedures were used to deduce a prediction rule from over 186 variables; retrospectively collated from clinical data for 213 patients. The resulting prediction rule was validated on independent data from a cohort of 158 patients described by Bhangu et al. (Colorectal Disease, 12(3):241-246, 2010).

Results

Serum albumin levels (g/L) (P = 0.001), respiratory rate (resps /min) (P = 0.002), C-reactive protein (mg/L) (P = 0.034) and white cell count (mcL) (P = 0.049) were predictors of all-cause mortality. Threshold levels of serum albumin ≤ 24.5 g/L, C- reactive protein >228 mg/L, respiratory rate >17 resps/min and white cell count >12 × 103 mcL were associated with an increased risk of all-cause mortality. A simple four variable prediction rule was devised based on these threshold levels and when tested on the initial data, yield an area under the curve score of 0.754 (P < 0.001) using receiver operating characteristics. The prediction rule was then evaluated using independent data, and yield an area under the curve score of 0.653 (P = 0.001).

Conclusions

Four easily measurable clinical variables can be used to assess the risk of mortality of patients with Clostridium difficile infection and remains robust with respect to independent data.

Keywords:
All-cause mortality; Clostridium difficile related mortality; Non-Clostridium difficile related mortality; Clinical prediction rule